Double-tube return-bend



C. H. IBUE.. DOUBLE TUBE RETURN BENDfl APPLICATION FILED MAY24,1919

1,373,465; Patented Apr. 5, 1921.

cHAaLns HENDERSON TRUE, or HAMMOND,` INDIANA, AssrGNoR To THE SUPER.. HEATER cor/rrANY, or NEW Yonx, N. Y.. A coaronA'rioN or DELAWARE.

DOUBLE-TUBE RETURN-BEND.

Specification of Letters Patent.

vPatented Apr. 5, 1921.

Application filed. May 24, 1919. Serial No. 299,623.

To'aZZ whom t may concern.'

a s ecification. y

` y invention concerns itself with pipe arrangements in which one set of pipe lies within another, the ends of each set-of pipes being connected by return bends so that independent inner and outer conduits are formed. It has for itspurpose the provision of an improved form of the return bends connecting the pipes and anovel mode of making them. The advantages of a return bendaccording to the present invention and of the proposed method of making it will appear clearly from the following description. This description is to be read in connection with the accompanying drawing. In the latter, Figures 1 and 2 show portions of two of the outer and two of the inner pipes connected, the one by an incomplete and the other by a substantially i N complete return bend; Fig. 3 illustrates the same two parts placed into the relative p osition which they are to occupy finally; Fig.

4 is a section on line 4-4 on Fig. 3; Fig.

5 shows the returnbend after an additional step has been taken toward finishing it; Fig. 6 shows the completed double-pipe return bend; Fig. 7 is a longitudinal central section of F-ig. 6 taken at right angles to it; Fig. 8 illustrates a modification; Fig..

9 is a section on line 9--9 of Fig. 8; Fig.

10 shows a furthermodication.

In makingthe constituent parts of my double-pipe return bend, I ein loy the method described fully in U. S. atent 1,169,209 to myself and N. T. McKee -as joint inventors. The complete return bend illustrated in Fig. 1 is made by the process described in that patent. The die employed in its manufacture is usually referred to as a breeches die on account of -its shape and will be so referred to hereinafter. The return -bend as shown in Fig. 1 will hereinafterbe -referred to as an incomplete return bend. By it, the two pipes 1 and 2 are joined,- the material being portions of the pipes themselves. The st-ructureis at this stage open at the end 3. It is assumed herein that the readeris familiar with'the patent mentioned above and with this art in general and no detailed description of the process of making this incomplete return bend is believed necessary. The structure illustrated in F ig. 2 consists of the two pipes 4 and 5 joined at their ends by a return bend 6, which, it will be noticed, is closed at its end 7 and has projecting from it a relatively long nub 8. This return bend 6 is -made by thesame process as the one` of Fig. 1 and is closed preferably by swa ing machine as fully described in U. S. Patent 1,255,355 to myself and C. A. W. Brandt as joint inventors. The pipes 4 and 5 will be seen in Fig. 2 to have received a double bend or offset at the points 9 and 10. This is for the purpose of placing the axes of the pipes 4 and 5 the same distance apart as those of the pipes 1 and 2 of the structure of Fig. 1. It will be understood that the pipes 1,y 2, 4 and sired length.

The two structures thus 'briefly described are placed one inside of the other as illus-- trated in Fig. 3. They areheld in-this relative Iposition by any means desired. Thereafter the incomplete return bend of the outer structure is suitably heated and swaged down as at 11 in Fig. 5. By an additional step which is merely a continuation of the swaging just spoken of, this return bend is finally closed as shown in Fig.

6. It will be found to advantage in practice, during the step of drawing down the outer incomplete return bend to the shape of Fig. 5, to that its crotch 12 will be in contact with @the point 13 of the inner structure, and to hold the two in the relative position they are to occupy, only during the additional step of giving -it the shape of Fig. 6. The nub 8 as well as the portion 11 are heated to a welding heat for this last step. In this manner, the wall 11 and the nub 8 become one integral structure and this connection serves to hold the inner return bend in fixed relation to the outer.

Undercertain circumstances it may be undesirable to hold the two sets of pipes in this relatively fixed position. In such cases, I do not provide a nub 8 on the inner return bend (see Fi 8) but rely on supports 14 for keepingt e two properly spaced. This 5 are of any de-l place the inner structure so cylindrical portion l5.

I which the inner return bend instead of being closed and provided with a nub 8 is left open and is provided with al connecting The outer return bend is drawn down and connected to it as shown. This is of utility in certain places.

It will be manifest that numerous variations, not only in the method employed in producing my double-tube return bend, but

valso in the return bend itself will occur in practice.

What I claim is:

1. The process of making'double-pipe return bends comprising the steps of connecting the ends of two pipes by an incomplete return bend, connecting the ends of two smaller pipes to form a complete return bend, inserting the latter into the former so that the two are substantially coaxial, and then finishing the incom lete bend.

2. The process of making double-pipe return bends comprising the steps of connecting the ends of two pipes by an incomplete return bend by the breaches die operation,

Vconnecting two smaller pipes to form a coming the ends of two pipes by an incomplete return bend, connecting two smaller pipes to form a complete return bend, provided with a terminal projection, inserting the latter pair into the former and swaging down and closing the end of the incomplete return bend uniting it to the projecy tion.

4. The process of making double-pipe return bends comprising the steps of connecting the ends of two pipes by an incomplete return bend, connecting the 'ends of two smaller pipes to form a complete return bend, inserting the latter into the former so that the two are substantially coaxial, providing `means to keep the two relatively spaced and inally closing the incomplete re turn bend.v

CHARLES HENDEIISON TRUE. 

